Recently, as a new memory device, a semiconductor memory device called Resistance Random Access Memory (RRAM) is noted. The RRAM uses a resistance memory element which has a plurality of resistance states of different resistance values which are changed by electric stimulations applied from the outside and whose high resistance state and low resistance state are corresponded to, e.g., information “0” and “1” to be used as a memory element. The RRAM is considered prospective because of the high potentials of the high speed, large capacities, low electric power consumption, etc.
The resistance memory element has a resistance memory material whose resistance states are changed by the application of voltages sandwiched between a pair of electrodes. As the typical resistance memory material, oxide materials containing transition metals are known.
The semiconductor memory device using the resistance memory element is disclosed in, e.g., U.S. Pat. No. 6,473,332, Japanese published unexamined patent application No. 2005-025914, Japanese published unexamined patent application No. 2004-272975, Japanese published unexamined patent application No. 2004-110867, Japanese published unexamined patent application No. 2004-355670, A. Beck et al., Appl. Phys. Lett., Vol. 77, p. 139 (2001), W. W. Zhuang et al., Tech. Digest IEDM 2002, p. 193, and I. G. Baek et al., Tech. Digest IEDM 2004, p. 587.
However, the conventional method of simply applying a voltage to the resistance memory element to thereby change the state of the resistance memory material from the low resistance state to the high resistance state applies an excessive voltage to the resistance memory element. There is a risk that such an excessive voltage might change the resistance state of the resistance memory element from the high resistance state again to the low resistance state, and the high resistance state could not be retained.